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Subject: Re: King danger extensions

Author: Ulrich Tuerke

Date: 00:56:17 02/17/99

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On February 16, 1999 at 16:26:53, James Robertson wrote:

>My program keeps falling prey to king attacks. Although it does very well
>tactically when it's king is not threatened, it frequently plays combinations
>that win material (it thinks), only to find, say, a back-rank mate that went
>unnoticed. I am using a one-reply-to-check extension, the mate extension after
>null move, and extending half a ply whenever there is a check in the tree. No
>check detection is done in the q-search. Are there any other standard check
>extensions I am not doing?
>
>James

I have had similar problems regarding blindness for back-rank mates. I tried to
solve it this way: my the static evaluation determines if a king is on a weak
back rank (e.g only escape squares to same rank and neither friendly rook nor
friendly queen on the back rank to protect, ...). In this case the ecaluation
sets a flag, which controls the move generation of the queiscence in order to
also generate checking moves wth queen and rook to unprotected squares on the
weaked back rank ; seems to help and doesn't cost too much, if you do this only
close to the last full search ply.

Uli



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